>> well it's one thing we're doing the main thing now is significant energy efficiency, for example, different kinds of turbines. different kinds of processes, that sort of thing. that's right. >> the same sort of thing as with, for domestic uses, the energy-efficient light bulbs? >> well, i really don't think this is about light bulbs, mr. chief justice. >> no, but my point is it relates to energy consumption as opposed to particulate emission. >> at the at the moment that's largely true, not entirely true. there are some other technologies described. but of course the epa is considering and scientists are trying to develop additional control technologies like carbon capture technologies. and that's the whole point of best available control technology, is as technology advances and better options come online, that allow for even greater control of the pollutants, the statute requires that they be incorporated. that's how it's supposed to work. >> if you if you regulate -- i'm talking about your two distinct arguments in your in your brief. if you prevail on the first, in other words